Agressividade de Alternaria tomatophila, A. grandis e A. solani em batateira e tomateiro

• Ano de defesa: 2010
• Autor(a) principal: Cardoso, Carine Rezende
• Orientador(a): Mizubuti, Eduardo Seiti Gomide
• Banca de defesa: Brommonschenkel, Sérgio Hermínio , Fontes, Paulo Cezar Rezende
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal de Viçosa
• Programa de Pós-Graduação: Mestrado em Fitopatologia
• Departamento: Etiologia; Epidemiologia; Controle
• País: BR
• Palavras-chave em Português: Batata; Tomate; Epidemiologia; Alternaria tomatophila; Alternaria grandis; Alternaria solani
• Palavras-chave em Inglês: Potato; Tomato; Epidemiology; Alternaria tomatophila; Alternaria grandis; Alternaria solani
• Área do conhecimento CNPq: CNPQ::CIENCIAS AGRARIAS::AGRONOMIA::FITOSSANIDADE::FITOPATOLOGIA
• Link de acesso: http://locus.ufv.br/handle/123456789/4387

Early Blight is an important disease of potato and tomato crops worldwide. In Brazil, Alternaria solani was considered the only causal agent of early blight. Recently, A. grandis and A. tomatophila were found to be the main species associated with early blight in potato and tomato, respectively. Due to the novelty of these findings no studies about host specificity and ecological requirements were conducted yet. In other countries, there is evidence of host specificity in populations of Alternaria spp., including of A. solani, caused or largely influenced by differences in aggressiveness. In the current study, we quantified the effects of the main climatic variables on the following epidemiological variables: lesion area (LA), area under the curve of mycelial growth (AUCMG), infection frequency (IF), and incubation period (IP). Eleven isolates of Alternaria spp were studied: 6 isolates of A. grandis, 4 of A tomatophila and 1 of A. solani were inoculated in potato and tomato plants. The effects of temperature on mycelial growth (15, 22, 25 30, and 35 oC) and LA (18, 22, 25, and 30 oC) and the effects of duration of leaf wetness period (DLW) (2, 4, 8, 12, and 24 h) on IF and IP of Alternaria spp were assessed. Higher values of LA, IF and lower values of IP were observed in potato, regardless of the isolates. The higher susceptibility of potato 'Opaline' and the phenological stage at which the plants were inoculated influenced this result. Temperature differentially affected LA depending on the species x host combination. A. grandis, A. solani and A. tomatophila, caused higher LA in the original hosts. A. grandis was more aggressive than A. solani in potato and caused higher LA at low temperature and at 30ºC, but the optimum temperature for LA for all species was 25ºC. Mycelial growth of Alternaria spp. was affected by temperature. The highest growth was found for A. grandis. The optimum temperature for A. grandis, A. solani, and A. tomatophila was 24, 24, and 26 oC, respectively. The FI was affected by the DLW, but the effect varied according to the species x host combination. The values of IF were similar for all species in most DLW. However, under limiting conditions of 2 h of DLW in potato, A. grandis had higher IF values than A. solani and A. tomatophila. In tomato, similar IF values were recorded for all isolate of Alternaria spp. In the fall experiment no symptoms were observed in tomato plants inoculated with A. solani and the development of early blight was slower than in the summer experiment. There is evidence of host preference in the Brazilian populations of Alternaria spp. associated with early blight in potato and tomato, even though A. grandis and A. tomatophila can cause disease in both hosts.